Drill conduit for walls



March 28, 1944. w. M. M GREW DRILL CONDUIT FOR WALLS Filed March 19, 1941 INVENTOR/ \M/VILToN l7 GREw IIIJ 01 flTTOR/VEY. I

Patented Mar. 28, 1944 UNITED STATES PATENT OFFICE DRILL CONDUIT FOR WALLS Wallace Milton McGrew, Long Beach, Calif.

Application March 19, 1941, Serial No. 384,162

2 Claims.

This invention relates to a drill conduit for walls whereby holes are drilled through a wall, for example a concrete form, for the purpose of threading wire, or other element therethrough, to reinforce or support the form; that is, to prevent the form from spreading. The element which is passed through the drill may also be an electrical conduit, a pipe, a bolt, rope or the like.

An object of my invention is to provide a novel drill conduit, the outer tubular drill of which is removable from the driving transmission, and is used as a conduit through which the supporting wire or other element is threaded.

Another object is to provide a novel drill conduit consisting of an outer tubular drill, a pilot drill arranged within and coaxial with the tubular drill, the outer and inner drills preferably rotating in opposite directions.

A feature of my invention resides in the novel, simple and effective means to removably mount the outer tubular drill on the driving shaft.

A feature of my invention resides in the attachment to a standard drill motor which accommodates my form drill, and may be thus used as an attachment instead of a permanent fixture, if desired.

Other objects, advantages and features of invention may appear from the accompanying drawing, the subjoined detailed description or the appended claims.

In the drawing:

Figure 1 is a side elevation of my form drill mounted on a driving motor.

Figure 2 is a fragmentary longitudinal sectional view of the upper part of the tubular drill, and showing the releasable coupling.

Figure 3 is a fragmentary side elevation of the tubular drill.

Figure 4 is a fragmentary side elevation of the pilot drill.

Referring more particularly to the drawing, the numeral l indicates a driving motor which may be electrical or pneumatic or hydraulic, or hand, and includes the usual chuck 2. A gear box 3 may, if desired, be an integral part of the driving motor, or may be removably attached to the motor by means of a sleeve 4 fixedly attached to the gear box, and fastened to the motor I by means of the set screw 5.

The drive shaft 6 of the gear box extends into the chuck 2, thus driving the gears in the gear box. A driven shaft 1 extends from the gear box 3, and this driven shaft is tubular substantially as shown in Figure 2.

The outer tubular drill 8 has a relatively long shank so that it can pass entirely through the spaced walls of a concrete form, or the like. The drill passes transversely through these walls from side to side, and a wire or other element is subsequently passed through this tubular drill, and protrudes from both sides of the walls, thus permitting a workman to quickly and easily place this wire or conduit in position after the tubular drill has passed through the walls of the form.

A socket 9 is provided on the upper end of the drill 8, and this socket is so arranged that it will accurately receive the driven shaft 1. A pin If) on the driven shaft enters a bayonet slot l l in the socket 9, thus releasably holding the tubular drill in driving position on the motor I.

The pilot drill I2 extends axially through the tubular drill 8, and preferably protrudes from the lower end of the tubular drill substantially as shown in Figure l. The pilot drill l2 preferably rotates in opposite direction from the tubular drill 3. Also the pilot drill screws, or otherwise attaches, to one of the gears 13 of the gear box 3 or to the chuck 2 of the motor, the upper end of the pilot drill being threaded as shown at [4 for this purpose. The pilot drill is thus normally attached to the transmission 3 at all times.

After the drills have passed through the wall the socket 9 is released from the shaft 1, and the pilot drill I2 is pulled out of the tubular drill, thus leaving a clear opening through the tubular drill for the passage of the conduit wire or the like. After the wire, conduit, or flexible element has been run through the tubular drill this drill is also pulled out of the Wall, and is again attached to the transmission, and the operation may be repeated.

Having described my invention I claim:

1. A drill structure of the character described comprising a driving motor including a rotary shaft, a gear box associated with said motor, gearing in said box including an upper gear turning with the motor shaft and a lower gear turning in a direction opposite to that of the upper gear, a tubular shaft carried by the lower gear to turn therewith and projecting from the gear box, a pilot drill extending through said tubular shaft and having its upper end detachably connected to and turning with the upper gear, a tubular drill about said pilot drill having a collar at its upper end fitting about the protruding portion of said tubular shaft, said pilot drill projecting from the lower end of the tubular drill, and means detachably connecting said collar with said tubular shaft.

2. A drill structure of the character described a power shaft, a tubular drill rotatably fitting 10 about said pilot drill with the lower portion of the pilot drill protruding from the lower end of the tubular drill, a collar at the upper end of said tubular drill fitting about the protruding portion of said tubular shaft and formed with a bayonet slot, and a pin carried by the tubular shaft and engaged in the bayonet slot to detachably hold the tubular drill in engagement with the tubular shaft.

W. MILTON McGREW. 

